M&MA

  Design and Implement of QPSK Modem Based on FPGA. Abstract   : This paper presents a method to designs QPSK modulator and demodulator of a spread spectrum system which use field programmable device.  The method uses the tool of Quartus Ⅱ of American Altera Co. The whole system is divided into several small models based on top-down design method, and using VHDL hardware description language to design each model. 

WCDMA, HSPA, HSPA+, LTE          "An information system formed by HAP (High Altitude Platform) will be a new generation-system for the wireless communications and HAPS (HAP Station) communication system combines the advantages of both terrestrial and satellite communication systems and avoids, to different extents, their disadvantages. Third generation (3G) mobile technology which is specified by the third generation partnership project (3 GPP) is definitely one of the candidates. With the success of wireless network, the IEEE 802.16 standard, with its wireless metropolitan area network (MAN) air interface appears to be a strong competitor. We provide initial practical comparison of these two technologies for HAPS Communication". WCDMA HSPA HSPA+ LTE Maximum Uplink Speed 128 Kbps 5.7 Kbps 11 Mbps 50 Mbps Maximum Downlink Speed 14 Mbps 11 Mbps 28 Mbps 100 Mbps Spectrum FDD

Testability VLSI: Boundry scan Boundary scan is a test technique using scan methodology, involving digital services,  digital devices, designed with shift registers (scan flip flops) placed between each device pin and the internal logic.    These shift registers can control and observe signal values present at each input and  output pin and are connected together in serial fashion to form a data register chain,  called boundary scan shift register with shift and update stages.

JTAG Test Access Port JTAG Testability: JTAG Test Access Port Controller                                                             The TAP is a general-purpose port that can provide access to many test support functions built into a component, including the test logic defined by this standard. 

Comparison of nmos and pmos operation modes: For many years,  NMOS  circuits were much faster than comparable  PMOS  and CMOS circuits, which had to use much slower p-channel transistors. comparison of nmos and pmos operation modes comparison of nmos and pmos operation modes video:

Difference between Travelling wave tube and klystron: Difference between Travelling wave tube and klystron Travelling wave tube and klystron Video:

IPv4 address Analysis: An  IPv4 address  is a  32-bit  address that uniquely and universally defines the connection of a device (for example, a computer or a router) to the Internet. The IPv4 addresses are unique  and universal.

Definition & Basics :  "Multiplexing is the procedure in which numerous Data Streams, originating from diverse Sources, are joined and Transmitted over a Single Data Channel or Data Stream."      In Electronic Communications, the two fundamental types of Multiplexing are Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM).

Multiplexing And Multiple Access : Digital Communications Difference between Multiplexing and Multiple Access: Sr.No. Multiplexing Multiple Access 1 “In telecommunications and  computer networks, multiplexing is a process where multiple analog  message signals or digital data  streams are combined into one   signal over a shared medium.” “In telecommunications and computer networks, a channel access method or multiple access  method allows several terminals connected to the same multipoint physical medium to transmit over it and to share its capacity.” 2 The multiplexed signal is transmitted  over a communication channel,  which may be a physical transmission medium. A channel-access scheme is  based on a multiplex method  that allows several data streams  or signals to share the  same communication channel or  physical media.

Difference in between TDM and FDM: This page on FDM versus TDM describes  difference between FDM and TDM multiplexing . FDM is the short form of frequency division multiplexing and TDM is the short form of time division multiplexing. In FDM each signal is modulated onto different unique RF carrier frequency and all carrier frequencies are separated significantly so that bandwidth of the signals do not overlap in frequency domain. Figure: Difference in between TDM and FDM

Comparison between AC and DC servo systems : Sr. No. AC servo systems DC servo systems 1.                       Efficiency is low Efficiency is high 2.                       Low power output High power output 3.                       It requires less maintenance It requires frequent maintenance 4.                       Less stability problems More stability problems. 5.                      Smooth operation Noisy operation. 6.                      It has non-linear characteristic It has linear characteristic Comparison between AC and DC servo systems Video: Comparison of stepper motor with DC servo motor Basics of Multiplexing HOW MOBILE NETWORK WORKS WITH GMSK MODULATION TECHNIQUE ? Comparison in FDM and synchronus TDM and statistical TDM How Multiplexing of signals in Fiber Optical cable

Comparison of stepper motor with DC servo motor : sr . No. Stepper motors DC servo motor 1. Control winding is not present. Control wingding              is present 2. Stepping              rate        is governed by frequency of switching and not by supply voltage. Does not rotate in steps. 3. Number of steps can be precisely controlled by controlling the number of pulses. DC servo motor gives continuous rotation. 4. Brushes are absent. Brushes are present 5. Maintenance is low High  maintenance 6. Due        to            load/no                load conditions no change in running current. Due        to            load/no                load conditions           sufficient change in            running current. Comparison between AC and DC servo systems Comparison of stepper motor with DC servo motor